Aqueous electrolyte energy storage device

An electrochemical device comprising:

• a housing;
• a stack of electrochemical cells in the housing, each electrochemical cell comprising:
• an anode electrode;
• a cathode electrode;
• a separator located between the anode electrode and the cathode electrode;
• and
• an electrolyte;
• a current collector located between adjacent electrochemical cells;
• an anode bus operatively connected to the anodes of the electrochemical cells in the stack;
• and
• a cathode bus operatively connected to the cathodes of the electrochemical cells in the stack,
• wherein, the anode electrode, the anode bus and the cathode bus comprise graphite
• wherein the cathode electrode comprises a doped or undoped cubic spinel -MnO2-type material or NaMn9O18 tunnel structured orthorhombic material, the anode electrode comprises activated carbon and the electrolyte comprises sodium ions;
• wherein the electrochemical cells in the stack of electrochemical cells are stacked in a prismatic configuration, wherein:
• the anode electrode of each electrochemical cell in the prismatic stack is electrically connected to the anode bus;
• the anode electrodes of the electrochemical cells in the prismatic stack are electrically connected in parallel to the anode bus;
• the anode bus is electrically connected to a positive contact which protrudes outside the housing;
• the cathode electrode of each electrochemical cell in the prismatic stack is electrically connected to the cathode bus;
• and
• the cathode electrodes of the electrochemical cells in the prismatic stack are electrically connected in parallel to the cathode bus;
• and
• the cathode bus is electrically connected to a negative contact which protrudes outside the housing.